Green Crits under nat 20's?

I'm having an issue with one of my players character sheets where when I roll their attack (whether it be their Rapier or Dagger) and they get below a 20, the number turns green and it's registered as a crit. Not exactly sure whats going on here but other sheets are fine. They're an Aasimar Bard, not sure if that matters.

That "cs>11" in the damage roll is what's happening. It's treating any roll 11 or higher as a crit. Open the attack on the sheet and edit the base damage. it should just be 1d20. If it is already just 1d20, look for the "crit range" field on the attack. It likely has an 11 sitting in there. It should be "20" (or possibly blank, I can't remember how the D&D 5th Edition by Roll20 Sheet treats a blank field in that attribute).